Reactive Lymphoid Tissues Research Articles

Expression of retinoblastoma protein and P16 proteins in classic Hodgkin lymphoma: relationship with expression of p53 and presence of Epstein-Barr virus in the regulation of cell growth and death

Deregulation of several genes involved in cell cycle control has been reported in classic Hodgkin lymphoma (cHL). This study aimed to investigate the expression of tumor suppressor proteins (P16(INK4A), retinoblastoma protein, and p53) in cHL in relation to the proliferation and apoptosis of Hodgkin/Reed-Sternberg (H/RS) cells, correlating with the status of Epstein-Barr virus (EBV). A total of 66 cHL cases and 10 nonneoplastic reactive lymphoid tissues were retrieved from the archives. Immunohistochemistry technique was used for the detection of protein expression. Presence of EBV infection was detected by EBV early RNA in situ hybridization. p16(INK4A) gene deletion status was assessed by fluorescence in situ hybridization technique. Expression of P16(INK4A) was observed in 49.2% of the cases, whereas positive retinoblastoma protein and p53 expressions in the H/RS cells were detected in 89.1% and 81.5% of the cases, respectively. Epstein-Barr virus positivity was detected in 53.0% of the cases. Proliferation marker, Ki-67 expression, was observed in 86.7% of the cases. There was no significant correlation between the expression of the various tumor suppressor proteins and Ki-67. Retinoblastoma protein and p53 were also not associated with the presence of EBV. An inverse relationship was observed between the expression of P16(INK4A) and the presence of EBV. There were no significant homozygous or hemizygous deletions of the p16(INK4A) gene. However, an aberrant copy number of chromosome 9 with the loss of one or more p16(INK4A) loci was detected in all cases assessable by fluorescence in situ hybridization. Loss of function of one or more tumor suppressor proteins may be involved in defective cell regulation of H/RS cells. Epstein-Barr virus may have a role in inhibiting P16(INK4A) expression, thus resulting in a perturbed p16(INK4A)-Rb cell cycle checkpoint.

CD14 and CD169 expression in human lymph nodes and spleen: specific expansion of CD14 +CD169 − monocyte-derived cells in diffuse large B-cell lymphomas

The mononuclear phagocyte system of human lymphoid tissue comprises macrophages and dendritic cells (DCs). The heterogeneity of the non-DC mononuclear phagocyte population in human lymphoid tissue has been little addressed. Here, we studied the expression of 2 monocyte-derived markers, CD14 and CD169 (sialoadhesin), in reactive human lymphoid tissue as well as in a series of 51 B-cell lymphomas by immunohistochemistry on paraffin-embedded tissue. We confirmed that lymph node sinusoidal monocyte-derived cells were the only population staining for CD169. Although most sinusoidal histiocytes also expressed CD14, monocyte-derived cells with phagocytosis such as erythrophagocytosis, anthracosis, or tingible bodies macrophage lacked CD14 and CD169. Among B-cell lymphomas, splenic marginal zone lymphoma was the only one associated with an expansion of the CD14(+)CD169(+) cells in the cords. With respect to nodal B-cell lymphomas, CD14(+) cells were rare among B-chronic lymphocytic leukemia, follicular lymphoma (FL), mantle cell lymphoma (MCL). However, strikingly, we found a strong expansion of CD14(+)CD169(-) cells in numerous diffuse large B-cell lymphomas (DLBCLs), except in cases associated with numerous mitoses, apoptotic bodies, and tingible bodies macrophages. When cultivated in granulocyte/macrophage colony stimulating factor/interleukin 4, DLBCL purified CD14(+) cells differentiate into plasmacytoid cells, expressing DC-specific intercellular adhesion molecule 3-grabbing nonintegrin, suggesting dendritic cell differentiation potential. Our observation fits well with the lymph node and host response cluster signatures described in the gene profiling signatures of DLBCL. However, the role of this CD14(+) population that may constitute a microenvironment-related marker of this subgroup of DLBCL remains to be determined.

FOXP3 Expression in B and T Cell Lymphomas.

Foxp3, which encodes a forkhead/winged helix transcription factor designated Scurfin, is a key regulatory gene required for the development and function of regulatory CD4+CD25+ T cells (Treg), a subpopulation of T-cells specialized in maintaining the balance between immunity and tolerance.Humans with defects in the FOXP3 gene, develop strong activation of the immune system, leading to multiorgan autoimmune disease, allergies, inflammatory bowel disease and severe infections, collectively known as the IPEX syndrome (immune deregulation, polyendocrinopathy, enteropathy, X-linked inheritance syndrome)Because of the importance of FOXP3 in the development and function of Treg cells, and its potential use as a specific Treg marker, we have developed several monoclonal antibodies against FOXP3, for use on paraffin-embedded tissue sections and evaluated its expression in a large series (150 cases) of B- and T-cell lymphomas. In reactive lymphoid tissue, strong nuclear FOXP3 expression was observed in approximately 5% of interfollicular T-cells. FOXP3 expression in tumour cells was confined to most of Adult T-cell Leukaemia/Lymphoma (ATLL) cases (68%), with some variability in protein expression. In other lymphoma types, FOXP3 expression was only detected in the reactive T-cell background, and the number of FOXP3-positive reactive T-cells was variable, ranging from almost a complete absence (Burkitt's lymphoma) to abundant infiltrate (common in follicular lymphoma).In conclusion, the availability of a FOXP3 monoclonal antibody, not only provides an important tool for the study of the development and function of Treg cells, but also represents a useful marker for the identification of ATLL cases in formalin-fixed paraffin-embedded tissue sections.The presence or absence of Treg cells in the tumour environment could also play a role in the immune surveillance of tumours, thus implying a potential additional value for the detection of this cell population in tumour samples.

Expression of X-Linked Inhibitor of Apoptosis Protein in Reactive Lymphoid Tissues, Non-Hodgkin's Lymphomas, and Hodgkin's Disease.

X-linked inhibitor of apoptosis protein (XIAP) is an important regulator of apoptosis which binds to and inhibits caspases-3, -7 and -9, blocking the caspase 9-mediated apoptosis pathway. This pathway is activated by p53 and DNA damage and may be an important determinant of responsiveness to chemotherapy. Apoptosis also plays a major role in the regulation of follicle center B-cell proliferation and BCL2-mediated inhibition of apoptosis is a key factor in B-cell lymphomagenesis. In this study we examined the expression of XIAP in 65 reactive and neoplastic lymphoid proliferations utilizing a monoclonal antibody to XIAP (#610763 BD Biosciences, San Jose, CA) and immunohistochemistry with avidin-biotin-complex immunoperoxidase technique on formalin-fixed, paraffin-embedded sections. In reactive lymph nodes and tonsils, expression of XIAP was limited to large noncleaved cells in follicle centers (5 of 6 cases). XIAP was absent in plasmacytoma (3 cases) and small lymphocytic lymphoma/chronic lymphocytic leukemia (1 case). XIAP was expressed in follicular lymphoma, predominantly in large noncleaved cells (6 of 9 cases) and in diffuse large B cell lymphoma (11 of 16 cases), including cases of T-cell/histiocyte-rich diffuse large B cell lymphoma (2 cases), primary mediastinal large B cell lymphoma (1 case), and posttransplantation diffuse large B cell lymphoma (1 case). XIAP was consistently expressed in Burkitt and Burkitt-like lymphoma (3 of 3 cases) and anaplastic large cell lymphoma (3 of 3 cases) and in one case of adult T cell leukemia/lymphoma. XIAP was variably expressed in marginal-zone B cell lymphoma, predominantly in large blasts (2 of 4 cases) and in mantle cell lymphoma (2 of 3 cases). XIAP was not detected in peripheral T cell lymphoma, unspecified (1 case), extranodal NK/T cell lymphoma, nasal type (1 case), precursor B cell lymphoblastic leukemia (1 case), or granulocytic sarcoma (1 case). XIAP was consistently expressed in the Reed-Sternberg and mononuclear Reed-Sternberg-variant cells of classical Hodgkin disease (9 of 9 cases) and the L+H Reed-Sternberg-variant cells of nodular lymphocyte predominance Hodgkin disease (3 of 3 cases). XIAP is expressed across a broad range of lymphoproliferative disorders, including classical and nodular lymphocyte predominance Hodgkin disease, diffuse large B cell lymphoma, follicular lymphoma, Burkitt lymphoma, marginal-zone and mantle cell lymphoma, and anaplastic large cell lymphoma. XIAP appears to be selectively expressed in the proliferating elements of these lymphomas. The possible prognostic and therapeutic significance of XIAP expression needs to be determined.

BAFF-R, the major B cell–activating factor receptor, is expressed on most mature B cells and B-cell lymphoproliferative disorders

B cell-activating factor receptor (BAFF-R) is one of three known receptors for BAFF, a critical regulator of B- and T-cell function. In mice, BAFF-R is required for B-cell maturation and survival, and in mice and humans, the overproduction of BAFF is associated with autoimmune disease. We sought to determine the normal pattern of BAFF-R expression at specific stages of B- and T-cell development and whether this pattern of expression corresponds with related B- and T-cell neoplasms. Most circulating human B cells and a small subset of T cells are BAFF-R-positive. In reactive lymphoid tissues, BAFF-R is expressed by B cells colonizing the mantle zones, by a subset of cells within germinal centers, and rare cells in the interfollicular T-cell zone. BAFF-R is also expressed by B cells colonizing the splenic marginal zone. Seventy-seven (78%) of 116 cases of B-cell lymphoproliferative disorders were BAFF-R-positive by immunohistochemical and/or flow cytometric immunophenotypic analysis, including most cases of mantle cell lymphoma, follicular lymphoma, marginal zone lymphoma, chronic lymphocytic leukemia, hairy cell leukemia, and diffuse large B-cell lymphoma. In contrast, cases of precursor B lymphoblastic lymphoma, Burkitt lymphoma, and nodular lymphocyte-predominant Hodgkin lymphoma exhibit weak to negative staining for BAFF-R. All cases of classical Hodgkin lymphoma and T-cell lymphomas were BAFF-R-negative, including all cases of anaplastic large cell lymphoma, adult T-cell leukemia/lymphoma, angioimmunoblastic T-cell lymphoma, and peripheral T-cell lymphoma, unspecified. These findings highlight BAFF-R as a marker of both normal and neoplastic B cells and raise the possibility that BAFF-R expression is necessary for the survival of a subset of neoplastic B lymphocytes analogous to its known role in promoting normal B-cell maturation and survival.

The CD45 isoform B220 identifies select subsets of human B cells and B-cell lymphoproliferative disorders

The B220 isoform of CD45, a pan B-cell marker in mice, is expressed by only a subset of human B cells that do not express the memory B-cell marker CD27, suggesting that it is a differentiation-specific isoform of CD45. We examined normal human peripheral blood B cells, secondary lymphoid tissue, and a range of human B-cell lymphoproliferative disorders for the expression of B220 by flow cytometric immunophenotyping and immunohistochemical staining. We found that a subset of human B cells in peripheral blood is positive for B220 by flow cytometric immunophenotypic analysis. In reactive lymphoid tissues, B220 is expressed by B cells occupying the mantle zones and by a subpopulation of germinal center cells, but, in contrast, marginal zone B cells in the spleen do not express B220. Of 94 cases of B-cell lymphoproliferative disorders, 33 (35%) were positive for B220 by flow cytometric immunophenotypic analysis, including most cases of marginal zone lymphoma, follicular lymphoma, and lymphoplasmacytic lymphoma. In contrast, all cases of precursor B lymphoblastic leukemia/lymphoma, mantle cell lymphoma, and chronic lymphocytic leukemia/small lymphocytic lymphoma were negative for B220. Immunohistochemical staining for B220 correlated with flow cytometric analysis for all cases studied by both methods. Our data demonstrate that B220 is expressed in a select subset of normal, reactive B cells in a pattern that is consistent with a marker of naive B cells. However, this restricted expression pattern is not seen in B-cell lymphoproliferative disorders. Discordance between the B220 expression patterns of normal mantle and marginal zone B cells and their respective neoplastic counterparts may aid in the distinction between normal and neoplastic proliferations at these anatomical sites.

Abnormal PcG protein expression in Hodgkin's lymphoma. Relation with E2F6 and NFkappaB transcription factors.

The Polycomb group (PcG) of proteins comprises a family of repressors of homeobox genes that play key roles in body formation, haematopoiesis and cell cycle control. In this study, a large-scale analysis of PcG protein expression (BMI1, MEL18, PH1, RNF2, RING1, and RYBP) was performed in 321 Hodgkin's lymphoma (HL) biopsies and in reactive lymphoid tissues using tissue microarrays. The relevance of PcG proteins in HL was also investigated by the simultaneous analysis of PcG and other proteins involved in the control of cell cycle, transcription machinery and lymphoid differentiation. The analysis revealed increased expression of a set of PcG proteins (particularly RYBP and BMI1) in tumour cells in comparison with reactive lymphoid tissue. One of the most striking findings was anomalous RYBP expression in 55% of classical HL cases associated with an unfavourable response to treatment and shorter survival. The data obtained in this study also show an association of PcG proteins with E2F6 and NFkappaB transcription factors. The statistical relationship between PcG and NFkappaB activation was further explored in HL-derived cell lines treated with curcumin, an NFkappaB inhibitor, and TNFalpha. Up- or downregulation of MEL18 was paralleled by loss or gain of activated NFkappaB, which suggests that NFkappaB may regulate expression of this protein. Investigation of the relationship between E2F6 and RING1 by immunofluorescence and confocal analysis, in HL cell lines and paraffin sections, revealed co-expression of both proteins in the same tumour cells. These results allow us to propose that the formation of transcription complexes with E2F6 may modify the functional status of PcG proteins in HSR cells.

Nasal NK/T Cell Lymphoma in Taiwan: A Clinicopathologic Study of 22 Cases, with Analysis of Histologic Subtypes, Epstein-Barr Virus LMP-1 Gene Association, and Treatment Modalities

Nasal NK/T cell lymphoma is a distinctive type of extranodal lymphoma with an unique immunophenotype and a strong association with Epstein-Barr virus (EBV). It is one of the common extranodal lymphomas in Taiwan. We studied 22 cases of nasal NK/T cell lymphoma to characterize their clinicopathologic features and to explore the possible differences between histologic subtypes and their clinical behavior as well as the prevalence of 30-base pair (bp) deleted latent membrane protein-1 (LMP-1) gene of the EBV. They consisted of 5 cases of small cell type (SC), 6 cases of medium-sized cell type (MC), 6 cases of large cell type (LC), and 5 cases of pleomorphic cell type (PC). Twelve patients were men and 10 were women (1.2 to 1), and their ages ranged from 34 to 75 years with a median age of 55.5 years. The median ages of the LC type and PC type were older than the other 2 types. No other clinical features differed significantly among the 4 subtypes. Nasal obstruction was the most common initial presenting symptom. All but 1 case had stage IE disease at the time of diagnosis. Five cases developed extranasal involvement and skin was the most common site. No bone marrow involvement was detected. The majority of patients received local radiotherapy and chemotherapy. Local irradiation was more effective than chemotherapy alone. We achieved an overall survival of 63.6% at 5 years as estimated by the Kaplan-Meier analysis, which was better than other series. All cases displayed an immunophenotypic profile of CD3(epsilon)+, CD20-, CD56+, and TIA-1+ except that 1 case was CD3(epsilon)-. Fourteen of 22 cases (64%) expressed LMP-1. Nine cases of various cell types (41%) were also CD30+. Among the 4 histologic subtypes, the SC type differed from the other types by the absence of angiodestruction and necrosis, although angioinvasive growth was seen in 2 of them. Pseudoepitheliomatous hyperplasia was seen in only 3 cases of the SC type, and all 5 cases of the SC type were CD30-. No statistical difference in survival was found among the 4 histologic subtypes or between CD30+ and CD30- cases. All 22 cases were positive for EBV by polymerase chain reaction and Epstein-Barr virus early RNA (EBER) in-situ hybridization. A high prevalence rate of 86% (19/22) of the 30-base pair (bp) deleted LMP-1 gene was found, but 81.5% (22/27) of the EBV-positive control reactive lymphoid tissues also had the 30-bp deleted LMP-1 gene. Therefore, the high prevalence of the 30-bp deleted LMP-1 gene found in NK/T cell lymphoma could be due to the high prevalence of the deleted variant in this geographic region. However, it remains possible that the high prevalence of the deleted LMP-1 gene contributed to the increased incidence of EBV-associated nasal NK/T cell lymphoma in Taiwan.

Levels of B7-2 in tumor cells of Hodgkin’s disease

T cell activation requires two signals: one is antigen-specific and controlled by major histocompatibility complex (MHC) proteins, the other is antigen-independent and primarily mediated through members of the B7 protein family. The tumor cells in classical Hodgkin’s disease (cHD) express both MHC and B7 proteins, yet recognition of cHD tumor cells by T cells is inadequate. Quantitative analysis showed that tumor cells in cHD-involved tissue expressed similar levels of MHC II proteins as did antigen-presenting cells in reactive lymphoid tissue. In contrast, B7-2 levels were significantly lower in cHD tumor cells. These findings suggest that enhancing costimulatory signals might represent a promising therapeutic approach to overcome the poor immunogenicity observed in cHD tumor cells.

FDC-B1: a new monoclonal antibody directed against bovine follicular dendritic cells.

Follicular dendritic cells (FDCs) are a unique population of accessory cells located in the light zone of the germinal centres of lymphoid follicles. Their involvement in the generation of humoral immune responses implies a potential role for these cells in many disorders. Indeed, in prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein expression and the principal sites of the infectious agent accumulation in lymphoid organs. The identification of FDC is useful for the analysis of their distribution in reactive lymphoid tissue as well as in pathological conditions. The production and characterisation of a new mouse monoclonal antibody directed against bovine follicular dendritic cells (FDC-B1) is reported. The antigen detected by FDC-B1 is expressed exclusively on the surface of FDCs in ruminant lymphoid organs. The antigen has an approximate molecular weight of 28 kDa.

FcgammaRIIB is differentially expressed during B cell maturation and in B-cell lymphomas.

FcgammaRIIB, a low affinity receptor for the Fc portion of immunoglobulin G (IgG), is thought to drive negative selection of B cells in germinal centers (GC) by inducing apoptosis upon interaction with immune complexes. Its expression was investigated by immunohistochemistry in 22 reactive lymphoid tissues and 112 B-cell lymphomas. Pre-GC mantle cells, marginal zone cells and their neoplastic counterparts expressed FcgammaRIIB. The B chronic lymphocytic leukaemia (B-CLL)/small lymphocytic lymphomas were also positive. Not detected in GC, FcgammaRIIB was expressed in 52% of follicular lymphomas and in 20% of diffuse large B cell lymphomas (DLBCL). In DLBCL, FcgammaRIIB expression was linked to transformation (P < 0.001). Re-analysis of a gene profile data set from the Lymphochip microarrays showed that FcgammaRIIB expression in the activated B-like DLBCL subgroup was higher than in the GC-like one (P < 0.04), and was associated with an adverse prognostic both in univariate (P < 0.003) and in multivariate analysis including the International Prognostic Indicator (IPI) (P < 0.01). Thus these results challenge the potential role of FcgammaRIIB during B-cell selection in GC, and suggest a prognostic value of FcgammaRIIB expression in DLBCL.

Telomerase activity in B-cell non-Hodgkin lymphomas is regulated by hTERT transcription and correlated with telomere-binding protein expression but uncoupled from proliferation.

Telomere maintenance is a prerequisite for immortalisation, and in most malignant cells is carried out by telomerase, an enzyme that synthesises new telomeric repeats on the chromosome ends. In normal or reactive tissues with a high regenerative capacity, telomerase is regulated according to the telomere loss that occurs during proliferation. To evaluate the interaction of proliferation and telomerase activity in malignant lymphomas, we quantified telomerase expression in different non-Hodgkin lymphomas in comparison to normal or reactive lymph nodes. Surprisingly, the activity levels were the same in most of the lymphomas analysed as compared to reactive lymph nodes. Significantly higher activity was detected only in Burkitt's lymphoma. Telomerase activity correlated well with hTERT and c-myc expression, but was independent of proliferation. To evaluate interactions of telomere-binding protein expression on telomerase expression in non-Hodgkin lymphoma, the mRNA levels of TRF1, TRF2, tankyrase and hPif1 were assessed by real-time RT–PCR. We demonstrate here that the magnitude of telomerase upregulation does not necessarily reflect the requirement of telomere compensation caused by proliferation. Telomerase regulation in non-Hodgkin lymphomas is therefore uncoupled from proliferative stimuli found in reactive lymphoid tissue. We suggest that the upregulation of specific telomere-binding proteins like TRF2 may contribute to telomere maintenance in malignant lymphoma.

LOWER EXTREMITY RADICULOPATHY IN A FEMALE MARTIAL ARTIST

HISTORY • 19 yo female Division I Lacrosse player presents for PPE without any complaints. She was quite busy with a relatively intense training schedule throughout the summer holiday, but recently (3–4 weeks prior) had to decrease intensity of work-outs due to sore throat and fatigue lasting 4 to 5 days. She decided against seeking treatment as it “was just a cold and it would pass”. She had made no attempts at weight gain or loss, but noted that her weight had increased 3 lbs over the course of the summer. She attributed the noted change to her increasing workloads in training sessions. She had sustained no prior injury during the off-season, had a “full physical” while at home, and “cleared for full activity” by her outlying physician. • PMHx: mild seasonal allergies. • PSHx: eyebrow lac 2001, ACL 1999. • FMHx: aunt with “thyroid problems”, remaining family ok. • SOHx: no tobacco, 1–4 alcoholic drinks per week, no illicit substance use, not sexually active. • No allergies or medications. • ROS: mild fatigue over past weeks, but improving; otherwise (-). PHYSICAL EXAM • T 99.4, P 66, BP 108/50, R 22, BMI 20 ÁOx3, NAD, mildly anxious. • HEENT: diffuse, marked, asymmetric thyromegaly (L > R). Thyroid 6x normal size, fixed, firm with smooth texture. No discreet palpable nodules within gland substance. One 2 to 3 cm firm lymph node closely associated with the superior pole the left, and several smaller shotty nodes in the right anterior cervical chain. No other adenopathy. • Remainder of PE was normal. DIFFERENTIAL DIAGNOSIS Thyroid disease — (autoimmune, infectious, neoplastic) Thyroiditis, likely Hashimoto's autoimmune. Lymphatic disease — (reactive/infectious, neoplastic). TESTS & RESULTS Chemistries — TSH, T3 & T4 all normal. — CBC with differential & CMP normal. — Anti-thyroglobulin and anti-thyroid AB's (+). Ultrasound — Heterogeneous thryomegaly, 2x3cm nodule lft superior lobe. — Multiple lesions of varying sizes in left parajugular region. Biopsy (US-guided) — FNA: lymphocytic thryoiditis with abnormal B-cell population, suspicious for malignancy. — Additional FNA (adjacent node): reactive lymphoid tissue only. — Excisional biopsy (original node): samples sent to Mayo Clinic and NIH: both showing a B-cell Lymphoma, follicular type, grade 2/3. • Additional Testing — PCR: Monoclonal B-cell population, flow cytometry negative. — Bone Marrow Biopsy: normocellular, no evidence of lymphoma. — PET Scan: increased activity in the thyroid region. — CT of Chest-Abdomen-Pelvis: negative for malignancy. FINAL/WORKING DIAGNOSIS Idiopathic Auto-Immune Thyroiditis with an associated reactive lymphoid process. TREATMENT & OUTCOMES Thryroid: daily hormone replacement, currently stable, asymptomatic, and within therapeutic range. Monthly follow-up visits with Endocrinology and Oncology. Enjoying Lacrosse and training at full participation level.

Development of a Real-Time Reverse Transcription Polymerase Chain Reaction Assay for c-myc Expression That Allows the Identification of a Subset of c-myc+ Diffuse Large B-Cell Lymphoma

Absence of a reliable method for determining the level of c-myc expression has impeded the analysis of its biological and clinical relevance in tumors. We have standardized the conditions for a real-time reverse transcription polymerase chain reaction analysis for c-myc expression, including the selection of an endogenous reference (18S rRNA), the adequate number of measurements for each sample (2 cDNA in triplicate), and suitable controls for determining inter- and intrarun variability (standard curve and calibrator). Subsequently, in a series of 56 non-Hodgkin's lymphomas, we analyzed the expression of c-myc mRNA, using real-time reverse transcription polymerase chain reaction, and of other functionally related proteins (bcl-6, p27, cyclin D3, and p53). As expected, all eight Burkitt's lymphoma cases analyzed had high levels of c-myc mRNA expression compared with that observed in reactive lymphoid tissue. There was a wider range of expression in diffuse large B-cell lymphoma, with 30% (15 of 48) of cases overexpressing c-myc. This overexpression was largely independent of c-myc translocations (4 of 5), as demonstrated by fluorescence in situ hybridization. In this large B-cell lymphoma series, a high level of c-myc expression predicted lower survival probability, irrespectively of the International Prognostic Index risk group classification. A slightly increased frequency of p53 inactivation was observed in the cases with c-myc overexpression, which suggests a growth advantage in lymphomas with concurrent deregulation of c-myc and p53. In addition, a moderate increase in bcl-6 protein expression was observed in the c-myc–positive cases, suggesting the existence of a complex interrelationship between these two genes. These findings suggest that c-myc may play a relevant role in the pathogenesis of a subset of large B-cell lymphoma and suggest the existence of additional regulatory mechanisms of c-myc expression to c-myc rearrangements.

Vascular patterns in reactive lymphoid tissue and in non-Hodgkin's lymphoma.

The few studies published on angiogenesis in lymphoma have raised the question of whether or not microvessel density (MVD) is associated with more aggressive disease and have reported the observation that in follicular lymphomas, vessels are mature rather than immature. We investigated MVD and the vascular phenotype within follicular or diffuse large B-cell lymphomas, reactive nodes and tonsils. Vascular phenotype was defined by the expression or loss of reactivity to the antibody LH39 (detecting the LH39 laminin epitope of the basement membrane in mature vessels) and by detection of αVβ3 (expressed on immature vessels). In reactive nodes and in follicular lymphomas, MVD was higher in the paracortex than in germinal centres or in neoplastic follicles. However, in neoplastic follicles an increase in αVβ3-positive endothelium suggested the activation of an angiogenic pathway different from that present in the reactive follicles. In large B-cell lymphomas, MVD was higher than in reactive and neoplastic follicles but lower than in the reactive paracortex. The number of immature vessels (LH39 negative) and of αVβ3-positive vessels was higher than in reactive lymph nodes and follicular lymphoma suggesting that a switch to a different angiogenic pathway has occurred. Finally, we have demonstrated that within reactive and neoplastic follicles vascular regression is occurring, perhaps constraining the growth of reactive follicles alongside other phenomena such as apoptosis. Vascular regression was previously believed to occur in adults only in ovarian and endometrial tissue. We conclude that different types of angiogenesis are present in follicular lymphomas and large B-cell lymphomas. This has implications for possible future therapies.

Detecting Clonal Rearrangement in Non-Hodgkin's Lymphomas in Taiwan by Polymerase Chain Reaction

The detection of monoclonal expansions of the immunoglobulin heavy chain (IgH) or the T-cell receptor- γ (TCR γ ) chain genes is an important supplement for the diagnosis of the non-Hodgkin's lymphomas (NHLs). Detection of monoclonality by polymerase chain reaction (PCR) method has offered an efficient approach for rapid diagnosis and monitoring of the therapeutic effects. Here we conducted a retrospective PCR clonality study on 49 cases of NHLs including 23 B-cell lymphomas (BCLs), 20 peripheral T-cell lymphomas (PTCLs), 6 natural killer (NK)/T-cell lymphomas and 3 reactive lymphoid tissues from southern Taiwan. Genomic DNAs from paraffin sections were extracted and analyzed by the IgH- and TCR-specific PCR reactions. The results showed that 20 of 23 (87.5%) BCLs exhibited IgH gene rearrangements and were all germline for TCR γ. 15 of 20 (75.0%) PTCLs exhibited TCR γ gene rearrangements while 1 case (5%) was positive for IgH gene rearrangement. The 6 NK/T-cell lymphomas and 3 reactive lymphoid tissues were all germline for either IgH or TCR γ genes. Our results were similar to other Western reports in terms of sensitivity and cell-lineage specificity. This is the first large series of PCR clonality study of IgH and TCR γ gene rearrangements on NHLs from Taiwan. We have confirmed that this rapid method is a sensitive diagnostic tool for NHLs.

Epstein-Barr virus-Associated Lymphomas in Malaysia: High Frequency of a 30-bp Deletion in the Viral Latent Membrane Protein-1 (LMP-1) Oncogene

A variant of Epstein-Barr virus (EBV) with a 30-base pair (bp) deletion in the latent membrane protein-1 (LMP-1) gene has been reported in many EBV-associated malignancies at different frequencies in different geographical locations. This study aims to determine the frequency of this variant in Asian EBV-associated lymphomas. We analyzed a total of 81 cases of known EBV-associated lymphomas [20 classical Hodgkin's, 19 Burkitt's, 33 T-and natural killer (NK)/T-cell, and 9 diffuse large B-cell lymphomas (DLBCL)] and 19 reactive lymphoid tissues from the archives. The presence of the 30-bp deletion at the 3' end of the LMP-1 gene was demonstrated by hybridization of polymerase chain reaction (PCR) products after amplification with a pair of primers flanking the deletion region. The DNA from 96.3% (78/81) of the lymphomas and 78.9% (15/19) of the reactive lymphoid tissues were amplified by PCR. The lymphomas showed infection by the deleted variant in 91.0% (71/78) of the cases, including 33.3% (26/78) cases with dual variant infection. The deleted variant was observed in 100% (19/19) of the Burkitt's lymphoma, 89.5% (17/19) of the classical Hodgkin's lymphomas, 90.6% (29/32) of the T-and NK/T-cell lymphomas and 75.0% (6/8) of DLBCL, whereas it was detected in 60.0% (9/15) of the reactive lymphoid tissues. The difference in the frequency of deleted LMP-1 variants observed between the lymphomas and the reactive lymphoid tissues was statistically significant (p=0.006). A significant difference was also observed between childhood and male lymphoma patients and reactive lymphoid controls of comparable age or gender group (p<0.001 and p=0.012 respectively). In conclusion, a high frequency of the 30-bp deletion in the LMP-1 gene was observed in the Malaysian population. The significantly higher percentage of deleted variant observed in EBV-associated lymphomas suggests the possibility of a selection mechanism during malignant transformation.

Comparative Analysis of Light Chain Expression in Germinal Center Cells and Mantle Cells of Reactive Lymphoid Tissues

We studied skewing of light chain ratios (LCRs) in germinal center cells (GCCs) relative to mantle cells (MCs) by flow cytometry (FC) in 98 reactive lymphoid tissues. LCRs were assessed using a 4-color lambda/kappa/CD20/CD38 tube. GCCs and MCs were discriminated by CD20 and CD38 density. Of 98 cases, 65 contained distinct GCCs and MCs. Light chain expression usually was dimmer on GCCs than on MCs; in 22 cases, the kappa and lambda clusters converged and accurate LCRs could not be determined. Of the remaining 43 cases, the mean GCC LCR was 1.78 (range, 1.10–3.07) vs 1.56 (range, 1.00–2.24) in the MCs ( P = .001). The overall kappa/lambda ratio in cases containing GCCs and MCs was 1.65 (range, 1.18–2.69) compared with 1.46 (range, 1.00–1.98) in cases containing MCs only. Of 43 cases, 19 (44%) showed differences of 20% or more between the LCRs of GCCs and MCs. LCRs of GCCs and MCs may differ substantially in reactive lymphoid tissues. These subsets may form distinct clusters and skews in their LCRs and should not be misinterpreted as evidence of occult lymphoma.

Epstein-Barr Virus (EBV) Subtypes and Variants in Malignant Tissue from Malaysian Patients

Epstein-Barr virus (EBV) is a ubiquitous virus that infects more than 90% of the world's population. In Malaysia this virus has been well documented in patients suffering from nasopharyngeal carcinoma, Hodgkin's lymphoma, and Burkitt's lymphoma. This study investigated the viral subtype and variant through the latent membrane protein-1 (LMP-1) gene taken from EBV-infected cancers in Malaysian patients. Nested polymerase chain reaction assays of EBV nuclear antigen-2 and single step polymerase chain reaction on the C-terminus of the LMP-1 gene were performed for virus typing and detection of a 30-bp deletion, respectively. Samples were obtained from 39 cases of nasopharyngeal carcinoma, 48 cases of Hodgkin's lymphoma, 19 cases of Burkitt's lymphoma and 19 cases of non-neoplastic reactive lymphoid tissues. All the tumors harbored EBV type A. Both the deleted and non-deleted variants were observed in the malignant tissues. In some cases, there was concurrent dual expression of both variants. Statistical analysis showed a significantly higher percentage of 30-bp deletions in cases of malignancies compared to reactive tissues. In conclusion, EBV type A predominates in Malaysian cancers, with a significant representation of the 30-bp deleted variant.

Fluorescence PCR Quantification of Cyclin D1 Expression

We have used a continuous fluorescence monitoring method to assess cyclin D1 mRNA expression in a variety of hematological and non-hematological processes. We examined 14 cell lines, 11 reactive lymphoid tissues, and 57 primary hematopoietic neoplasms including mantle cell lymphoma (MCL) (n = 10), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) (n = 11), acute lymphoblastic leukemia/lymphoma (n = 15), follicular lymphoma (n = 6), peripheral T-cell lymphoma (PTCL) (n = 3), anaplastic large cell lymphoma (n = 3), hairy cell leukemia (n = 3), Burkitt lymphoma (n = 1), Burkitt-like lymphoma (n = 4), and plasmacytoma (n = 1) for the expression of cyclin D1 mRNA using fluorescently labeled sequence-specific hybridization probes. Fluorescence (F) was plotted against cycle (C) number over 45 cycles. The log-linear portion of the F versus C graph identified a fractional cycle number for threshold fluorescence. A beta-globin mRNA transcript with equivalent amplification efficiency to that of cyclin D1 was used for assessment of RNA integrity and normalization. In general, the MCLs demonstrated substantially higher levels of cyclin D1 mRNA than the other lymphoproliferative processes. Moderately high levels of cyclin D1 mRNA were detected in one PTCL. On average, the CLL/SLL cases showed cyclin D1 mRNA levels two to three orders of magnitude lower than observed in the MCLs. Cell lines derived from non-hematopoietic neoplasms such as fibrosarcoma, small cell carcinoma, and neuroblastoma showed comparable or higher levels of cyclin D1 mRNA than the MCLs. Our results indicate that quantitative real-time reverse transcription (RT) polymerase chain reaction is a simple, rapid, and accurate technique for assessing cyclin D1 expression, and while it is not specific, it can reliably be used in the distinction of MCL from CLL/SLL.